Flex or T&E?

[GaryMo]

521.9.3 A flexible cable or flexible cord shall be used for fixed wiring only where the relevant provisions of the Regulations are met.

One such example being that the minimum size should be 0.75mm2.

Eric, it doesn't matter if flex is only rated at 60 degrees C as long as it's selected according to its current carrying capacity.

And ColJacks explanation of why SY cable is excluded from those that are acceptable for burial at a depth of less than 50mm without RCD protection is blindingly obvious.

 

[skenk]

It's a nonsense, give the average diyer a 40mm long wall plug and a drill with a 100mm long masonry bit. Ask them to drill a hole for the wall plug I guarantee most of them will drill a 100mm deep hole.

Well I think you'd struggle to drill a 100mm hole with a 100mm bit but I always drill deep enough that the plug is well into the brick or something solid, 40mm is rarely enough.

They make up for the times I drill a 37mm one, and end up having to trim the plug flush with the wall with a Stanley knife

So the plug is only in the plaster? - No1 cause of things screwed to the wall falling down! Usually because the DIYer only has a cheap cordless 'drill' and can't get into the brick.

I expected better of You, BAS!

 

[securespark]

Plaster must be thicker in Scotland....

But 37mm thick????

 

[skenk]

The feeble drill and bit (and diyer) make a bit of a dent in the softer outer brick then hit a harder piece of brick. You need a decent hammer drill to go any further.

Sometimes the walls have been re-skimmed 2 or 3 times or someone has dotted and dabbed on top of inch thick plaster.

 

[ban-all-sheds]

So the plug is only in the plaster? - No1 cause of things screwed to the wall falling down! Usually because the DIYer only has a cheap cordless 'drill' and can't get into the brick.

I expected better of You, BAS!

Ah - I should explain. Apart from a few localised areas which have been the subject of past DIY alterations, my walls have a coat of mortar, not browning or bonding (yes, really), and then a thin (barely 1mm in places) skim of finishing.

 

[LoveRocket]

And ColJacks explanation of why SY cable is excluded from those that are acceptable for burial at a depth of less than 50mm without RCD protection is blindingly obvious.

You'd have to be FOOKIN' good to get a nail through the gaps in the braid on a small SY!

As for split-con not being earthed all the way round, the other half being the neutral - well that's the whole point - the picture-hanger's nail will be in contact with EITHER earth or the neutral before hitting a phase conductor, thus the OPD will operate and you live to hang another picture.

 

[GaryMo]

I've seen SY cable with braiding far looser than the example above. Whilst it's possible to contact a live conductor before the braid it will always be excluded.

 

[ban-all-sheds]

Just what is SY well suited for?

 

[GaryMo]

Flexible supplies to machinery (ceeform plug and socket) and remote controls on machinery are two examples

 

[ban-all-sheds]

Why not other flexible cables?

We've recently seen (//www.diynot.com/forums/viewtopic.php?t=229602) that it's no good with oil & grease, the braid can be cut with a knife and can possibly be penetrated without being touched, so that's mechanical protection out of the window, and presumably the braid can't be used as a cpc.

 

[shetland]

Just what is SY well suited for?

Strain relief and abrasion resistance make it good for applications where it will be hanging from a socket for example, or as extension leads.

 

[SteNova]

i've had quite a few bits in work made with sy, usually for temporary supplys i'm connecting from other areas or from generators during planned electical work or supply outages, quite often it's out of aluminium windows etc so the cable gets some abuse, i also specd it to be used on a 80kVA ups installation to avoid it looking pants

 

[ColJack]

SY is used where EM interferance from the cable is undesireable ( such as inverter driven motors etc ), or where there is a need to shield cables from external EM interferance ( such as some signal cables etc. )..

 

[ColJack]

As for split-con not being earthed all the way round, the other half being the neutral - well that's the whole point - the picture-hanger's nail will be in contact with EITHER earth or the neutral before hitting a phase conductor, thus the OPD will operate and you live to hang another picture.

there's the possibility there to hit the neutral but not the live, leaving you with a nail at neutral potential..

if that happens to be a fair way from the TN interface, or a broken neutral etc then there could be a fair PD between the N and Earth..
lean on a rad while hanging a new picture and you're in trouble..

 

[ban-all-sheds]

Maybe that's what our friend the bonding expert has been on about...